Combustion of fossil fuels and in particular oil derived fuels such as gasoline and diesel is never completely efficient. The consequences of inefficient combustion range through high fuel consumption, a build up of carbon on cylinder heads and on pistons, variations in motor efficiency and production of excess amounts of noxious bi-products such as carbon monoxide, partially burnt hydrocarbons and nitrogen oxides (“NOx”).
Various fuel additives have been proposed to improve fuel economy and reduce combustion exhaust pollutants. Unburnt and partially burnt fuel represent both pollution of the combustion process and a financial loss to a purchaser of the fuel. The prior art has suggested adding combustion improvers for diverse types of fuel usages including flame burners, diesel engines, gasoline internal combustion engines and various turbine configurations. These prior art additives have been in various forms such as in a liquid state mixed with liquid carriers and some in a solid state as appropriate for the combustion system under review.
U.S Pat. No. 4,129,421 to Webb discloses a catalytic fuel additive for use in engines or furnaces. The additive employs a solution of picric acid and ferrous sulphate in specified alcohol. An example shows the additive employed for use in gasoline engines at levels supplying around 10 parts per billion of the combined catalyst. The disclosure indicates higher but unspecified levels of use for heavy fuel oils. In all cases the catalyst, is fully dissolved in the fuel.
U.S. Pat. No. 2,402,427 to Miller and Liber discloses the use of broad groupings of diesel-fuel-soluble organic and organo metallic compounds as ignition promoters at concentrations of from 0.02 to 3% (ie. 200-30,000 parts per million).
Among the early patents on catalytic metal fuel additives, U.S. Pat. Nos. 2,086,775 and 2,151,432 to Lyons and McKone disclose adding from 0.001 to 0.0085% (ie. from 10-850 parts per million) of an organo metallic compound or mixture to a base fuel such as gasoline, benzene, fuel, oil, kerosene or blends to improve various aspects of engine performance. Among the metals disclosed in U.S. Pat. No. 2,086,775 are cobalt, nickel manganese, iron, copper, uranium, molybdenum, vanadium, zirconium, beryllium, platinum, palladium, chromium, aluminium, thorium and the rare earth metals such as cerium.
Those disclosed in U.S. Pat. No. 2,151,432 include solanum, antimony, arsenic, bismuth, cadmium, admeium, tellurium, thallium, tin, barium, boron, cesium, didymium, lanthanum, potassium, sodium, tantalum, titanium, tungsten and zinc. In both patents, the preferred organo metallic compounds were beta diketone and derivatives and their homologues such as the metal acetylacetonates, proprionyl acetonates, formyl acetonates and the like.
The Lyons and McKone disclosures state that concentrations of from 0.001 to 0.04% (ie. from 10-400 parts per million) are not effective to improve combustion efficiency as introduced, but may become so upon prolonged use as catalytically active deposits are built-up in the combustion chamber. The disclosures further state that about 0.01% (ie. 100 parts per million) of the organo metallic compound is usually sufficient, once the requisite amount of catalytically active deposits have been built up to perpetuate the amount of deposits by replacement of losses therefrom.
U.S. Pat. Nos. 4,891,050 and 4,892,562 to Bowers and Sprague disclose the use of fuel soluble platinum group metal compounds which were effective at what was labelled “extremely low concentrations” to improve fuel economy in gasoline and diesel engines respectively. In this context, extremely low levels were seen as being in the range of 0.01 to 1.0 parts per million of the platinum group metal compared to the fuel to which it was added.
U.S. Pat. No. 4,629,472 describes the use of 0.005 to 0.5 parts per million catalyst to fuel oil when the catalyst was measured as metal on a weight basis. The preferred range of catalyst was 0.02 to 0.06 parts per million (ie. 2 parts per 100 million to 6 parts per 100 million). It is apparent that the prior art teaches there is a lower limit at which catalysts cease contributing significantly to the combustion process. As noted earlier, the Lyons and McKone documents indicated that concentrations of around 10-400 parts per million of catalyst were only effective once an adequate amount of catalytically active build-up arose.
Even U.S. Pat. No. 4,129,421 to Webb indicated a level of 1 part per 100 million as necessary to provide a significant effect. It would be of advantage if a method could be described to provide combustion enhancement at lower levels of additive than previously used.